When http4s met MUnit

Integration library between MUnit and http4s.

---

• Installation
• Contributors to this project
• Usage
  • Testing HttpRoutes
  • Testing AuthedRoutes
  • Using a mocked http4s Client
  • Testing a remote HTTP server
  • Testing an HTTP server running inside a container
• Other features
  • Running an effect before running your test
  • Tagging your tests
  • Stress-testing
  • Nested requests
  • Test names
  • Body in failed assertions
  • Response clues

Installation

Add the following line to your build.sbt file:

libraryDependencies += "com.alejandrohdezma" %% "http4s-munit" % "1.1.0" % Test

Contributors to this project

alejandrohdezma	gutiory	JackTreble

Usage

This library provides a new type of suite (Http4sSuite) that you can use for several things:

Testing HttpRoutes

We can use the Http4Suite to write tests for an HttpRoutes using Request[IO] values easily:

import cats.effect.IO

import org.http4s._

class MyHttpRoutesSuite extends munit.Http4sSuite {

  override def http4sMUnitClientFixture = HttpRoutes.of[IO] {
    case GET -> Root / "hello"        => Ok("Hi")
    case GET -> Root / "hello" / name => Ok(s"Hi $name")
  }.orFail.asFixture

  test(GET(uri"hello" / "Jose")).alias("Say hello to Jose") { response =>
    assertIO(response.as[String], "Hi Jose")
  }

  // You can also override routes per-test
  test(GET(uri"hello" / "Jose"))
    .withHttpApp(HttpRoutes.of[IO] { case GET -> Root / "hello" / _=> Ok("Hi") }.orFail)
    .alias("Overriden routes") { response =>
      assertIO(response.as[String], "Hi")
    }

}

The test method receives a Request[IO] object and when the test runs, it runs that request against the provided routes and let you assert the response.

http4s-munit will automatically name your tests using the information of the provided Request. For example, for the test shown in the previous code snippet, the following will be shown when running the test:

munit.MyHttpRoutesSuite:0s
  + GET -> hello/Jose (Say hello to Jose) 0.014s

Testing AuthedRoutes

If we want to test authenticated routes (AuthedRoutes in http4s) it will be completely similar to the previous section, except that we need to ensure we provide the context in the request. The library provides a couple methods to simplify this: context and getContext.

For both of them you need to have an implicit Key[A] instance (being A your context's type) in scope.

import cats.effect.IO

import org.http4s._
import org.typelevel.vault.Key

class MyAuthedRoutesSuite extends munit.Http4sSuite {

  implicit val key: Key[String] = Key.newKey[IO, String].unsafeRunSync()

  override def http4sMUnitClientFixture = AuthedRequest.fromContext[String].andThen {
    AuthedRoutes.of[String, IO] {
      case GET -> Root / "hello" as user        => Ok(s"$user: Hi")
      case GET -> Root / "hello" / name as user => Ok(s"$user: Hi $name")
    }
  }.orFail.asFixture

  test(GET(uri"hello" / "Jose").context("alex")).alias("Say hello to Jose") { response =>
    assertIO(response.as[String], "alex: Hi Jose")
  }

  // You can also override routes per-test
  test(GET(uri"hello" / "Jose").context("alex"))
    .withHttpApp {
      AuthedRequest.fromContext[String]
        .andThen(AuthedRoutes.of[String, IO] { case GET -> Root / "hello" / _ as _ => Ok("Hey") })
        .orFail
    }
    .alias("Overriden routes") { response =>
      assertIO(response.as[String], "Hey")
    }

}

Using a mocked http4s Client

If you just want to add tests for a class or algebra that uses a Client instance you can make your suite extend Http4sMUnitSyntax (it also requires extending CatsEffectSuite).

It includes a handful of utilities among which are two extension methods to the Client companion object: from and partialFixture.

Client.from lets you create a mocked client from a partial function representing routes:

import org.http4s.client.Client

class ClientSuiteSuite extends munit.CatsEffectSuite with munit.Http4sMUnitSyntax {

  val client = Client.from {
    case GET -> Root / "ping" => Ok("pong")
  }

}

On the other hand, the class also provides another extension method: Client.partialFixture. This method is inteded to be used to easily create a fixture for testing a class that uses an http4s' Client.

Given an algebra like:

import cats.effect._
import org.http4s.client.Client

trait PingService[F[_]] {

  def ping(): F[String]

}

object PingService {

  def create[F[_]: Async](client: Client[F]) =
    new PingService[F] {

      def ping(): F[String] = client.expect[String]("ping")

    }
  

}

You can test it using Http4sMUnitSyntax like:

import cats.effect._
import org.http4s.client.Client

class PingServiceSuite extends munit.CatsEffectSuite with munit.Http4sMUnitSyntax {

  val fixture = Client.partialFixture(client => Resource.pure(PingService.create(client)))

  fixture {
    case GET -> Root / "ping" => Ok("pong")
  }.test("PingService.ping works") { service =>
    val result = service.ping()

    assertIO(result, "pong")
  }

}

Testing a remote HTTP server

In the case you don't want to use static http4s routes, but a running HTTP server, you just need to provide a real http4s' Client implementation under http4sMUnitClient. Every test request you write will be made using this client.

import cats.effect.IO
import cats.effect.SyncIO

import io.circe.Json
import org.http4s.circe._
import org.http4s.client.Client
import org.http4s.ember.client.EmberClientBuilder

class GitHubSuite extends munit.Http4sSuite {

  override def http4sMUnitClientFixture: SyncIO[FunFixture[Client[IO]]] =
    ResourceFunFixture(EmberClientBuilder.default[IO].build.map(_.withBaseUri(uri"https://api.github.com")))

  test(GET(uri"users/gutiory")) { response =>
    assertEquals(response.status.code, 200)

    val result = response.as[Json].map(_.hcursor.get[String]("login"))

    assertIO(result, Right("gutiory"))
  }

}

If you are making requests to the same server, you can override http4sMUnitClientFixture like:

override def http4sMUnitClientFixture: SyncIO[FunFixture[Client[IO]]] =
  ResourceFunFixture(EmberClientBuilder.default[IO].build.map(_.withBaseUri(localhost.withPort(8080))))

Testing an HTTP server running inside a container

Testing a Docker container with TestContainers and http4s-munit is easy. You just need to use TestCotnainersFixtures and use Http4sSuite to connect to it:

import cats.effect.IO
import cats.effect.SyncIO

import com.dimafeng.testcontainers.GenericContainer
import com.dimafeng.testcontainers.munit.fixtures.TestContainersFixtures
import io.circe.Json
import org.http4s.client.Client
import org.http4s.circe._
import org.http4s.ember.client.EmberClientBuilder

class TestContainersSuite extends munit.Http4sSuite with TestContainersFixtures {

  // There is also available `ForEachContainerFixture`
  val container = ForAllContainerFixture {
    GenericContainer(dockerImage = "mendhak/http-https-echo", exposedPorts = List(80))
  }

  override def munitFixtures = List(container)

  override def http4sMUnitClientFixture: SyncIO[FunFixture[Client[IO]]] = ResourceFunFixture {
    EmberClientBuilder.default[IO].build.map(_.withBaseUri(localhost.withPort(container().mappedPort(80))))
  }

  test(GET(uri"ping")) { response =>
    assertEquals(response.status.code, 200)
    assertIOBoolean(response.as[Json].map(_.isObject))
  }

}

Or if you don't want to use container fixtures and you don't mind starting a container for each test:

import cats.effect.IO
import cats.effect.Resource
import cats.syntax.all._

import com.dimafeng.testcontainers.GenericContainer
import org.http4s.ember.client.EmberClientBuilder

class TestContainersSuite extends munit.Http4sSuite {

  lazy val container = GenericContainer(dockerImage = "nginxdemos/hello", exposedPorts = List(80))

  override def http4sMUnitClientFixture = ResourceFunFixture {
    Resource.fromAutoCloseable(IO(container.start()).as(container)) >>
      EmberClientBuilder.default[IO].build.map(_.withBaseUri(localhost.withPort(container.mappedPort(80))))
  }

  test(GET(uri"ping")) { response =>
    assertEquals(response.status.code, 200, response.clues)
  }

}

Other features

Running an effect before running your test

Sometimes (specially when you are testing against a real server) you need something to be run before running your test. On these cases, you can just create a ResourceFunFixture[Client[IO]] (in which you can add other effects) and run it with test.

Essentially this is the same as just running test since it is just an alias for http4sMUnitClientFixture.test.

import cats.effect.IO
import cats.effect.Resource
import cats.syntax.all._

import io.circe.Json
import io.circe.syntax._
import org.http4s.ember.client.EmberClientBuilder
import org.http4s.circe._

class MyBookstoreSuite extends munit.Http4sSuite {

  def httpClient = EmberClientBuilder.default[IO].build

  override def http4sMUnitClientFixture = ResourceFunFixture(httpClient)

  ResourceFunFixture {
    httpClient.flatTap { client =>
      Resource.make {
        val newBook = Json.obj("name":= "The Lord Of The Rings")

        client
          .expect[Json](POST(newBook, uri"http://localhost:8080/books"))
          .flatMap(_.hcursor.get[Int]("id").liftTo[IO])
      } { id =>
        client.run(DELETE(uri"http://localhost:8080/books" / id)).use_
      }.as(client)
    }
  }.test(GET(uri"http://localhost:8080/books?q=Rings")) { response =>
    assertEquals(response.status.code, 200, response.clues)

    val result = response.as[Json].map(_.hcursor.get[String]("name"))

    assertIO(result, Right("The Lord Of The Rings"), response.clues)
  }
}

Tagging your tests

Once the request has been passed to the test method, we can tag our tests before implementing them:

// Marks the test as failing (it will pass if the assertion fails)
test(GET(uri"hello")).fail { response => assertEquals(response.status.code, 200) }

// Marks a test as "flaky". Check MUnit docs to know more about this feature:
// https://scalameta.org/munit/docs/tests.html#tag-flaky-tests
test(GET(uri"hello")).flaky { response => assertEquals(response.status.code, 200) }

// Skips this test when running the suite
test(GET(uri"hello")).ignore { response => assertEquals(response.status.code, 200) }

// Runs only this test when running the suite
test(GET(uri"hello")).only { response => assertEquals(response.status.code, 200) }

// We can also use our own tags, just like with MUnit `test`
val IntegrationTest = new munit.Tag("integration-test")
test(GET(uri"hello")).tag(IntegrationTest) { response => assertEquals(response.status.code, 200) }

Stress-testing

http4s-munit includes a small feature that allows you to "stress-test" a service. Once the request has been passed to the test method, we can call several methods to enable test repetition and parallelization:

test(GET(uri"hello"))
  .repeat(50)
  .parallel(10) { response => 
    assertEquals(response.status.code, 200) 
  }

On the other hand, if you do not want to have to call these methods for each test, you also have the possibility to enable repetition and parallelization using system properties or environment variables:

• Using environment variables:

  export HTTP4S_MUNIT_REPETITIONS=50
  export HTTP4S_MUNIT_MAX_PARALLEL=10
  
  sbt test

• Using system properties:

  sbt -Dhttp4s.munit.repetitions=50 -Dhttp4s.munit.max.parallel=10 test

Also, when multiple errors occured while running repeated tests, you can control wheter http4s-munit should output all failures or not using:

# Using environment variable
export HTTP4S_SHOW_ALL_STACK_TRACES=true

# Using system property
sbt -Dhttp4s.munit.showAllStackTraces=true test

Finally, if you want to disable repetitions for a specific test when using environment variables or system properties, you can use doNotRepeat:

test(GET(uri"hello")).doNotRepeat { response => 
  assertEquals(response.status.code, 200) 
}

Nested requests

Sometimes one test needs some pre-condition in order to be executed (e.g., in order to test the deletion of a user, you need to create it first). In such cases, once the request has been passed to the test method, we can call andThen to provide nested requests from the response of the previous one:

test(GET(uri"posts" +? ("number" -> 10)))
    .alias("look for the 10th post")
    .andThen("delete it")(_.as[String].map { id =>
      DELETE(uri"posts" / id)
    }) { response =>
      assertEquals(response.status.code, 204)
    }

Test names

The generated test names can be customized by overriding http4sMUnitTestNameCreator. It allows altering the name of the generated tests.

Default implementation generates test names like:

// GET -> users/42
test(GET(uri"users" / "42"))

// GET -> users (all users)
test(GET(uri"users")).alias("all users")

// GET -> users - executed 10 times with 2 in parallel
test(GET(uri"users")).repeat(10).parallel(2)

// GET -> posts?number=10 (look for the 10th post and delete it)
test(GET(uri"posts" +? ("number" -> 10)))
    .alias("look for the 10th post")
    .andThen("delete it")(_.as[String].map { id => DELETE(uri"posts" / id) })

Body in failed assertions

http4s-munit always includes the responses body in a failed assertion's message.

For example, when running the following suite...

import cats.effect.IO

import org.http4s._

class MySuite extends munit.Http4sSuite {

  override def http4sMUnitClientFixture = 
    HttpRoutes.of[IO](_ => Ok("""{"id": 1, "name": "Jose"}""")).orFail.asFixture

  test(GET(uri"users"))(response => assertEquals(response.status.code, 204))

}

...it will fail with this message:

X MySuite.GET -> users  0.042s munit.ComparisonFailException: MySuite.scala:12
12:  test(GET(uri"users"))(response => assertEquals(response.status.code, 204))
values are not the same
=> Obtained
200
=> Diff (- obtained, + expected)
-200
+204

Response body was:

{
  "id": 1,
  "name": "Jose"
}

The body will be prettified using http4sMUnitBodyPrettifier, which, by default, will try to parse it as JSON and apply a code highlight if munitAnsiColors is true. If you want a different output or disabling body-prettifying just override this method.

Response clues

Apart from the response body clues introduced in the previous section, http4s-munit also provides a simple way to transform a response into clues: the response.clues extension method.

The output of this extension method can be tweaked by using the http4sMUnitResponseClueCreator.

For example, this can be used on container suites to filter logs relevant to the current request (if your logs are JSON objects containing the request id):

import cats.effect.IO
import cats.effect.Resource
import cats.syntax.all._

import com.dimafeng.testcontainers.GenericContainer
import io.circe.Json
import org.http4s._
import org.http4s.circe._
import org.http4s.ember.client.EmberClientBuilder
import org.typelevel.ci._

class TestContainersSuite extends munit.Http4sSuite {

  override def http4sMUnitClientFixture = ResourceFunFixture {
    Resource.fromAutoCloseable(IO(container.start()).as(container)) >>
      EmberClientBuilder.default[IO].build.map(_.withBaseUri(localhost.withPort(container.mappedPort(80))))
  }

  override def http4sMUnitResponseClueCreator(response: Response[IO]) = {
    val logs = response.headers
      .get(ci"x-request-id")
      .map(_.head.value)
      .map(id => container.logs.split("\n").filter(_.contains(id)).mkString("\n"))
      .getOrElse(container.logs)

    clues(response, logs)
  }

  lazy val container = GenericContainer(dockerImage = "mendhak/http-https-echo", exposedPorts = List(80))

  test(GET(uri"ping")) { response =>
    assertEquals(response.status.code, 200, response.clues)
    assertIOBoolean(response.as[Json].map(_.isObject), response.clues)
  }

}